Multiplet-specific shape resonance and autoionization effects in (2+1) resonance enhanced multiphoton ionization of O sub 2 via the d sup 1. Pi. sub g state

Journal Article · Tue May 01 00:00:00 EDT 1990 · Journal of Chemical Physics; (USA)

DOI:https://doi.org/10.1063/1.458511· OSTI ID:6903046

Stephens, J A; Braunstein, M; McKoy, V ^[1]

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1. Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125 (USA)

In this paper we discuss the single-photon ionization dynamics of the {ital d} {sup 1}{Pi}{sub {ital g}} Rydberg state of O{sub 2}. Comparision is made with vibrationally resolved measurements of photoelectron spectra which employ (2+1) resonance enhanced multiphoton ionization (REMPI) through the {ital d} {sup 1}{Pi}{sub {ital g}} state. A {sigma}{sub {ital u}} shape resonance near the ionization threshold leads to non-Franck--Condon vibrational branching ratios and a substantial dependence of photoelectron angular distributions on the vibrational state of the {ital X} {sup 2}{Pi}{sub {ital g}} ion. Significant differences exist between our one-electron predictions and experiment. These are mainly attributed to electronic autoionization of repulsive {sup 1}{Sigma}{sup {minus}}{sub {ital u}}, {sup 1}{Sigma}{sup +}{sub {ital u}}, and {sup 1}{Delta}{sub {ital u}} states associated with the 1{pi}{sup 3}{sub {ital u}}1{pi}{sup 3}{sub {ital g}} configuration. A proposed singlet {ital K}'' {sup 1}{Pi}{sub {ital u}} Rydberg state converging to the {ital A} {sup 2}{Pi}{sub {ital u}} ion probably also contributes to autoionization in the {ital d} {sup 1}{Pi}{sub {ital g}} state spectrum. We also show that autoionizing {ital H} and {ital J} {sup 3}{Pi}{sub {ital u}} Rydberg states of O{sub 2} converging to the {ital a} {sup 4}{Pi}{sub {ital u}} and {ital A} {sup 2}{Pi}{sub {ital u}} ionic thresholds, respectively, may play a previously unsuspected role in the {ital C} {sup 3}{Pi}{sub {ital g}} state one-color REMPI spectra. We discuss multiplet-specific (spin-dependent) effects via comparision of these results with recent experimental and theoretical studies of O{sub 2}{ital C} {sup 3}{Pi}{sub {ital g}} photoionization.

• DOE Contract Number: FG03-87ER60513
• OSTI ID: 6903046
• Journal Information: Journal of Chemical Physics; (USA), Vol. 92:9; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
OXYGEN
PHOTOIONIZATION
AUTOIONIZATION
ELECTRONIC STRUCTURE
MULTI-PHOTON PROCESSES
RESONANCE
ELEMENTS
IONIZATION
NONMETALS
640302* - Atomic
Molecular & Chemical Physics- Atomic & Molecular Properties & Theory
400500 - Photochemistry